1. Field of the Invention
This invention pertains to methods and apparatuses for controlling speed and direction of towing winches on vehicles and to improvements in the controls and the construction of such winches.
2. Description of the Prior Art
Winches for towing vehicles have, in the past, tended to be specially built for limited uses primarily because it was expensive and difficult to produce a winch meeting the requirement for the several different but specialized uses. A few attempts have been made to produce a winch and a method of controlling a winch which does provide more versatility without the inherent increase in expense and size of the winch. U.S. Pat. No. 3,729,171, for example, describes a method and a winch in which friction discs are used to selectively enable shifting from one direction to another at the output of the winch. U.S. Pat. No. 3,296,893, while not directed to a towing vehicle type of winch does have some features which are of value in controlling a winch. Both of these patented devices and method, however, do not provide sufficient versatility to be completely satisfactory. For example, the winch of the former patent requires varying independently the speed of the prime mover in order to obtain any change in speed of the winch drum and the hydraulic controls for operating the winch are expensive and very complicated to operate and maintain. In the latter patented device the winch is unable to provide a freewheeling condition which is essential in a towing winch for pulling out cable.